The present invention relates to glass or enamel lined columns or towers. Glass lined metal, particularly ferrous metal, steel, columns comprised of a plurality of individual sections, are subject to leakage at the gasketed junction of the column sections. Such leakage is caused by failure of the gasket, usually by an overloading of the gasketed joint. The present invention seeks to minimize, or eliminate, such overloading by providing a load sharing, or load distributing means, around the junction of the column sections.
Glass lined columns have found widespread use in numerous industries, particularly in those industries which utilize extraction, separation or distillation processes. The glass lining facilitates the use of such columns under severe adverse temperature and corrosion conditions. Such columns may be operated at atmospheric pressure, under a vacuum, or at pressures up to and exceeding 100 psi. Columns are typically comprised of a plurality of individual column sections. The sections are incrementally assembled facilitating the placement and arrangement of trays within the column as it is being assembled. If the column is to be packed, the packing is suitably placed in each section as it is assembled. Typically, the column sections have flanged ends and are separated at the flange interface by a resilient gasket. The gasket typically is fabricated of a plastic, e.g. fluorinated polymer, and includes layers of asbestos or corrugated stainless steel. The sections are placed together and the gasket compressed by means of clamps positioned around the outside circumference of the flanges. The objective is to obtain a leak-proof joint between the column sections.
The column sections may be assembled at the place of manufacture, or may be shipped in sections to the point of use and assembled in situ. Two methods are typically used. In one, the column is assembled on the ground, that is horizontally, and subsequently the assembled column raised to a vertical position. In the other method, the column sections are stacked, one by one, vertically until the column is complete.
When the horizontal assembly method is utilized, the final raising of the column places severe pressure and strain on the gasketed joints because the lifting, even carefully done, causes bending along the column length. As a result, the gaskets frequently become overloaded and present a leakage problem. Overloading is caused by the gasket being temporarily compressed so much that it loses its resiliency. When the overload is removed the gasket fails to take up the space at the junction of the column sections and results in leakage. This situation can be especially aggravating after pressure testing on the ground has shown no leakage.
When the column sections are stacked, the weight of each section bears upon the section or sections below. As the column height increases, the joint loading increases. If the column contains trays or is packed, the gasket loadings further increase. Typically, the weight of the column increases about in ratio of the square of the diameter.
In tall columns, other factors may contribute to overloading of the gasketed joints, for example, wind or sway that may cause the column to rock, or guy wires or cables that may be unintentionally over-tightened.